East Fork Lake Dam
East Fork Lake Dam is an earth dam located in Richland County, Illinois, built in 1972. It carries a High hazard potential classification.
About East Fork Lake Dam
The primary purpose of East Fork Lake Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by City Of Olney (local government). It impounds the East Fork Fox River near Olney.
The dam stands 84 feet tall and stretches 6,500 feet across, creates a reservoir covering 930 acres, has a maximum storage capacity of 22,680 acre-feet, and collects water from a drainage area of 10 square miles. Completed in 1972, the structure is well into its service life at over 50 years old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. An emergency action plan is in place for this dam. The most recent inspection on record was 08/28/2025.
At 84 feet, this dam is taller than 97% of all dams in the United States.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Illinois dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Illinois |
| County | Richland |
| Nearest City | Olney |
| River/Stream | East Fork Fox River |
| Coordinates | 38.76425, -88.07974 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 84 ft |
| Dam Height | 84 ft |
| Dam Length | 6,500 ft |
| Year Completed | 1972 (54 years old) |
Storage & Hydraulics
| NID Storage | 22,680 acre-ft |
| Max Storage | 22,680 acre-ft |
| Normal Storage | 12,460 acre-ft |
| Surface Area | 930 acres |
| Drainage Area | 10 sq mi |
| Max Discharge | 20,061 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | CITY OF OLNEY |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Not Available |
| Last Inspection | 08/28/2025 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL00334 |
| Federal ID | IL00334 |
| More Info | State Dam Safety Program |